The objective of the proposed research is to obtain further information on the biochemical and physiological characteristics of tumor cells using a Novikoff rat hepatoma cell line growing in suspension culture as a model system. It is hoped that such information may eventually lead to an understanding of the biochemical basis of the different growth behavior and regulatory responses of neoplastic and normal cells. Results from preliminary studies of glucose transport and metabolism have suggested that the uptake of glucose into the cell might be the rate-limiting step in its metabolism and consequently in the production of energy and metabolic intermediates required for growth. It is postulated that a change in the glucose transport system allowing for a more rapid uptake of glucose by the cells is one alteration of the cell surface of the neoplastic cell that is required for its more rapid growth rate. The immediate goals of the proposed investigation is to further study the mode(s) of uptake of glucose by the cells and to investigate the relationship between the rate of glucose transport and the growth rate of the cells. Another part of the study is concerned with the effect of hydrocortisone on the transport and metabolism of glucose. Studies will also be continued on the conservation of stable messenger RNA in Novikoff cells, the initiation of protein synthesis in whole cells and cell free preparations, and the processing of ribosomal precursor RNA. Finally, physiological and enzymological studies will be undertaken to determine if Novikoff cells are genetically locked into a unique metabolic pattern or if they exhibit their high glycolytic activity and classical enzymic profile because of the medium that must be used for growth.